MUSIC / Three magical flutes: Ensemble InterContemporain - Carnegie Hall

Composing can't be easy for Pierre Boulez. Not only have his past works set a staggeringly high standard - as he is no doubt aware, given how often he revises them - but he is one of the last remaining giants of the 1960s avant-garde and people expect his pieces to be some kind of compositional manifesto as well. A product of his preoccupation with computer-generated sound, Repons was a triumph in both regards. His latest work is neither.

. . . explosante / fixe . . . takes its title from a quotation by Andre Breton - 'Beauty shall be an immobile explosion or will not be' - and was first written in 1973. In its new version, it's a 35-minute piece for three solo flutes, chamber ensemble and computers, which meant that, at last Thursday's premiere, Carnegie Hall was outfitted with some 30 speakers.

Like most Boulez, . . . explosante / fixe . . . is full of iridescent textures and carries itself with a graceful, poetic air. The piece lacks the immediate appeal of Repons and, however fully realised each movement is individually, the three don't seem to belong together.

It sounds like a transitional piece. But these are observations rather than complaints. Boulez's artistry, and his use of computer-generated sound in conjunction with live instruments, has never been more subtle. While Philippe Manoury's The Division between Heaven and Hell, in the first half of the programme, used technology with an early-Lisztian virtuosity, the Boulez was more like late Liszt in its economy of gesture, and, in the final movement, searching inwardness.

The first two movements tend to pick up where Repons left off, using a lot of commonplace thematic material to build what often sounded like Lutoslawskian 'swarm' textures, with pillars of dissonance punctuating periods of great fantasy. Of the three flutes, one is connected to the computer, with its sound augmented way beyond the range, depth and speed normally possible; sometimes it is followed by two 'shadow' flutes. Mostly, the computer-generated sound completed chords, underscored the metamorphosis of a theme or echoed tolling bells. Themes imitated each other, sometimes staggered by only a split second, before winding down like clockwork and coming to a witty, urbane close.

The short, last movement immediately announces its difference from the other two with a wide-ranging, relatively lyrical melody for solo flute. The scoring is austere, with a rhapsodic lack of outward symmetry. It's intriguingly enigmatic, too. Yet it leaves a wonderful afterglow, and an even more interesting puzzle, being neither 'explosive' nor 'fixed'. Boulez's music has a history of consuming its poetic origins. Maybe this time he's carried it to the point of high irony.